Impulse transmitting arrangement



y 1933- R. TRECHCINSKI 1,908,574

IMPULSE TRANSMITTING ARRANGEMENT Filed Feb. 8. 1932 e. web/amp,-

lmr iz Fatented May 9, 1933 STATES raranr oFrics; 1

ROMAN TRECHGINSKI, F WARSAW, POLAND, ASSIGNO'R TO TELEFONAKTIEBOLAGET L.LM. ERICSSON, 0F STOCKHOLM, SWEDEN, A COMPANY OF SWEDEN IMPULSETRANSMITTING ARRANGEMENT Application filed February 8, 1932, Serial No.591,741, and in Sweden February 11, 1931.

The present invention refers to arrangements for the transmission ofimpulses over long lines. More particularly the invention refers toplants in which the impulses on the transmission line are generatedthrough reversals of the direction of the current in a local impulsecircuit which is inductively connected to the line. The current in thelocal impulse circuit is thus subjected to variations 19 which are equalto the double current amplitude, said current variations in turn causinginductive current impulses on the line. In impulse transmitting plantsof the kind in question at least two impulses are generated in additionto the impulses belonging to the impulse series, namely one impulse whenthe intermediate impulse circuit is energized and another impulse whensaid intermediate circuit is deenergized. Said extra impulses may insome cases be used for different purposes, but in other cases they areless desirable. The present invention has for its object to provide amethod for the elimination of said current impulses or other impulseswhich are not desirable and consists therein, that the transmission lineis in one or more places provided with arrangements for suppressingcertain impulses.

The invention will be more closely described with reference to theaccompanying drawing, in which Figure 1 illustrates diagrammatically theprinciple of the invention,

Figure 2 is a current diagram, and

Figure 3 illustrates an application of the invention.

In Figure l the reference numeral 1 designates the impulse contact of animpulse send er, for instance a finger disc. The impulse contact 1 isconnected in series with the wind ing 2 of a contact relay the contactset of which is arranged as .a current reverser or pole changer in alocal intermediate circuit including the primary winding of atransformer T the secondary winding of which is connected to thetelephone line L. Similarly to the impulse circuit proper the saidintermediate circuit is interrupted when a conversation is not going on.When the intermediate circuit is closed the positive pole of theappertaining impulse battery is connected to one terminal of thetransformer T by means of a choke coil 3 and a normally closed contact 4belonging to the contact set of the relay 2, and'the negative pole isconnected to the other terminal by means of a choke coil 3 and anormally closed contact 4 of the relay. The primary winding of thetransformer T is then passed by a current in the direction of the arrow7. When the relay 2 attracts its armature the contacts 4, 4 are openedand the poles of the battery are instead connected to the transformer bymeans of the normally open contacts 5, 5, the direction of the currentin the primary winding of the transformer being then. reversed. Inaccordance with the invention the secondary winding of the transformermay be arranged to be short-circuited by means of the contact 8 of arelay 9. Said relay is intended to beactuated only when not desirablecurrentsappear on the line.

Before starting the impulse sending, for instance when the subscriberlifts .off his microtelephone, the intermediate imp-ulseci-rcuitincluding the primary winding of the transformer T is closed. At themoment in question, which in Figure 2b is designated with t the currentin: thelocal circuit thusbegins to increase in a positive direction andwill after a certain short time reach its full value L. The closing ofthe impulse circuit proper, which circuit includes the relay winding 2,may, if desired, also be effectedwhen the microtelephone of thesubscriber is lifted off but is delayed somewhat by av suitablemechanical or electromagneti cal delaying arrangement and thereforetakes place first at the point of time 23 (Figure 2a) when the currentin the primary circuit of the transformer has already reached itsfullvalue. WVhen' the current was closed in the intermediate circuit a.current impulse a" (Figure 20). was, however, sent out on the linewhichcurrent impulse may serve to set the polarized relay 6 in itsstarting-position in casethe relay does not already take up thisposition.

When at the moment t the relay 2 attracts its armature the current inthe intermediate 1'00 impulse circuit is reversed by means of thecontact set in the above described manner and is thus subjected to avariation equal to 2L. On account of the reversal of the current in theprimary winding of the transformer a second impulse i is sent out on theline which impulse has twice as great an amplitude as the first impulse.Said impulse may serve to start the selecting operation, for instance byletting the polarized relay, upon being shifted, actuate a pre-selectoror searcher. When the subscriber thereafter actuates his impulse sender,thereby bringing about at the contact 1 repeated current interruptionsand current closing i of short duration, a series of correspondingcurrent reversals are caused in the intermediate circuit, in Figure 26designated with 2' and a corresponding series of alternate positive andnegative impulses 2' (Figure 20) are sent out on the line, said currentimpulses shifting the armature of the polarized relay 6 between its twopositions. The polarized impulse relay then in turn sends outcorresponding selector impulses.

When after completed conversation the subscriber hooks up hismicrotelephone the impulse circuit proper as well as the intermediateimpulse circuit are interrupted simultaneously at the moment Q, a finalimpulse 2' being then sent out on the line through which impulse thepolarized relay if required is returned to its starting position.

If it is instead desired to suppress the imulses i i and i the rela 9 isaccordin b to the invention controlled in such a manner, that thesecondary winding ofythe transformer T is short-circuited each time anyof said impulses appears in the same.

In the application of the invention illustrated in Figure 8 only partsofv the plant necessary for explaining the invention are shown. Adesignates, for instance, a subscribers set or the impulse sender of anoperator. The'impulses are sent through transformers T T and T T to orfrom a station not shown on the drawing, it being assumed in thefollowing that the impulses are sent from the subscribers position A.\Vhen the subscriber lifts off his microtelephone a circuit 10 is closedthrough the subscribers set, the primary windings of the transformers Tand T and the polarized relay PR The current impulse is not trans-.mitted over the line because the secondary windings of the transformersare short-circuited'through a contact 11 of a relay VR On account of thecurrent impulse the relay PR throws over its armature, then forming acircuit 12 for the relay IR which attracts its armature and in turncloses a circuit 13 for a relay SR which attracts its armature andprepares an impulse sending circuit 15. When attracting its armature therelay 1R also closes a circuit 14% for the relays GY,

and RU, the relay GY attracting its arma ture first and then the relayRU. By means of its normally open contacts 16 and 17 the latter relaynow closes the impulse circuit 15 through the primary windings of thetransformers T T a call signal being then sent over the line to thecall-ed station. At this time the relay VR attracts its armature, saidrelay being slow-acting when energized over the circuit 18, andinterrupts at its contact 19 the circuit 14 for the relays GrY and RU.Said relays are then deenergized in the following order. First the relayGY is deenergized, forming a circuit 20 for the relays GY and GY Aftersome time the relay RU is deenergized, interrupting the call signal. Theimpulse induced through the current variation at the interruption is,howeveiysuppressed thereby, that the short-circuit of the windings ofthe transformers T T is maintained by means of the contacts 21, 22, 23of the slow-acting relays GY GrY even for some time after the relay RUhas been deenergized. The times of operation of the relays GY and GrYare determined so that the subscriber may start the impulse sendingimmediately. Therelays PR IE and SR then pulsate in a predeterminedsequence. During the entire impulse series the relays RU and GrY keeptheir armature attracted and the current impulses are therefore, throughthe intermedium of the impulse circuit 15, sent through the transformersT and T to the called station. Also the relay GY is during the impulseseries maintained energized through the intermittently closed circuit47. Hereby the primary windings of the transformers T5, T areshort-circuited and the impulse sending is improved. The extra impulsez' occuring after each impulse series is suppressed in the abovedescribed manner thereby, that the relay GrY is deenergized previouslyto the relay RU, the former relay then closing the circuit for therelays GY and GY If it is now assumed that the wanted subscriber hasbeen called and lifts off his microtelephone an inductive impulse issent through the transformers T and T which impulse shifts the armatureof the relay PR and closes a circuit 24 for the relayVIR Said latterrelay is energized and closes a circuit 25 through the relay VR- Thisrelay attracts its armature and removes the short-circuit of thesecondary winding of the transformers T and T which are thereby preparedfor receiving the speech, and closes a circuit 26 for the relay GY.which attracts its 7 armature and closes a speaking circuit for thesubscriber A, said circuit having a small resistance. The twosubscribers may now start the conversation.

I claim:

1. In an arrangement for transmitting electric switching impulses, atelephone line,

a transformer, a direct current circuit connected to the said telephoneline by means of the said transformer, an impulse relay controlling thesaid direct current circuit and an auxiliary relay set adapted incooperation with the said impulse relay to suppress extra impulsesgenerated at the transmission.

2. An arrangement as claimed in claim 1, in which the auxiliary relayset is adapted to prevent a current interruption in the direct currentcircuit following upon a current closing in said circuit from causingimpulse generation in the telephone line.

3. In an arrangement for transmitting electric switching impulses, atelephone line, a transformer, a direct current circuit connected to thesaid telephone line by means of the said transformer, an impulse relaycontrolling the said direct current circuit, an auxiliary relay setadapted in cooperation with the said impulse relay to suppress extraimpulses generated at the transmission and to effect a current closingof short duration in the direct current circuit so as to bring aboutsuch an alteration in the circuit during the time interval between thecurrent closing and the subsequent current interruption that theinfluence of the current interruption on the telephone line isneutralized. I. An arrangement as claimed in claim 3, in which thesecondary winding of the transformer is adapted to be short-circuited inthe time interval between the current closing and the currentinterruption in the direct current circuit.

5. In an arrangement for transmitting electric switching impulses, atelephone line, a transformer, a direct current circuit connected to thesaid telephone line by means of the said transformer, an impulse relaycontrolling the said direct current circuit and adapted to effect areversion of the direction of the current in the direct current circuiteach time said relay attracts or drops its armature respectively, and anauxiliary relay set adapted in cooperation with the said impulse relayto suppress extra impulses generated at the transmission.

6. In an arrangement for transmitting electric switching impulses, atelephone line, a transformer, a direct current circuit connected to thesaid telephone line by means of the said transformer, an impulse relaycontrolling the said direct current circuit, an auxiliary relay setadapted in cooperation with the said impulse relay to suppress extraimpulses generated at the transmission and comprising two mutuallycooperating slowacting relays one of which is adapted to effect aclosing of short duration of the direct current circuit when the impulserelay attracts its armature whereas the other relay is adapted toshort-circuit the secondary Winding of the transformer whichshortcircuit lasts until the direct current circuit is interrupted.

In testimony whereof I aflix my signature.

ROMAN TRECHCIN SKI.

